This invention relates to the field of geophysical prospecting. More particularly, this invention relates to an apparatus and method for detecting underground minerals such as oil, gas, coal and other resources located beneath a body of water, such as a lake, pond or ocean. As used in this disclosure, the term "underground minerals" is used to designate both inorganic substances, such as mercury, and uranium, and organic substances, such as petroleum, gas, and coal.
Gaseous substances associated with water-covered subterranean deposits of minerals such as oil, gas and other materials, e.g. mercury and hydrocarbons, are known to migrate upwardly towards the earth's surface and in many cases to escape into the overlying body of water and be dissolved therein. In the past, efforts have been made to sample those gases reaching the earth's surface and those gases dissolved in the water, analyze the samples collected, and generate qualitative and quantitative data in order to locate promising deposits. The following U.S. Patents disclose several sampling devices and methods contrived in the past for this purpose:
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Known techniques represented by the disclosure of the above patents can be generally divided into two categories: techniques for collecting water samples and techniques for collecting sedimentary layer or subsedimentary layer core samples for subsequent analysis of the gaseous constituents therein.
It is now known that the concentration in the overlying water, sedimentary layer and subsedimentary soil of gases whose origins are deep varies significantly with time at any one location. Instantaneous sampling techniques, and sampling techniques utilizing relatively short time intervals, therefore do not yield reliable information relating to the concentration of such gases. In addition, many known techniques require the use of relatively expensive sampling equipment and highly skilled operating personnel, which results in a relatively high cost for obtaining information which is frequently of only marginal use.